There's some $6 billion in hundreds in that mountain, according to this estimate, or a billion in 20s. But in the otherwise fairly realistic Dark Knight financial world, with DAs investigating money laundering and the major crimes unit marking bills, a crazy person handed a teller a withdrawal slip, and their response was, "So did you bring a flatbed truck to haul this away, or do you need to rent ours? Also, do you want to sit down for three or four years and count it?"
I suppose Lau could have split the money into a hundred accounts or a thousand, but really, that only means even more tellers had to not give a shit about these incredibly shady bastards taking out literal tons of money in the middle of a citywide crackdown on organized crime. We shouldn't have even been surprised when thieves manage to bankrupt Wayne one movie later through the least sneaky fraud ever.
Over in the Marvel universe, Ultron's plan involves instantly sending Ulysses Klaue billions in exchange for his vibranium. It's a bizarre scene because Ultron could have just stolen the vibranium, and he indeed acts like he's going to (he throws Klaue through a glass window and ends up cutting off the guy's arm), but the point is that Ultron's power comes not from magic, but from his control of the internet. He's a less robotic Mark Zuckerberg.
Walt Disney Pictures
If this has you terrified about real hackers suddenly moving billions and bringing down whole economies, you may be relieved to learn that banks are much more worried about it than you are. That's why it always takes an actual human to approve those transactions, which is why when hackers got all the internet power they needed to siphon off a billion dollars a few years back, they only made away with a sliver of that before people noticed something fishy was going on. Or when other hackers steal millions, they can only do so by spacing it over a long time. That's right, the Office Space heist plan was real.